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Hello fellow coffee roasters. Like many of you, I started roasting using modified hot air poppers. That was about 4 years ago, but I found the quality, quantity and controls quite limiting. It also took many batches and a long time to roast a kilo... an upgrade was needed.

This fully manual 350g roaster was first designed using 3D CAD software. When the design felt right, I sourced for parts, 3D printed custom pieces, and hand crafted the current edition. Overall R&D took about a year, with multiple motors, iterations and materials being used and discarded.

There is only one active cyclone on the left side. The other one was cut (right side) in half and you only see the top cap of the unit, there is no bottom. This was done so I could use the same high temperature 3D printed mounts for both sides... a little more cost, but keeps it looking symmetrical.

I'm at work now, but later I will provide detailed build images, and a video that shows the machine function throughout the roast cycle. This unit doesn't have air recirculation. It can roast a 350g batch to city+, while spending about 425 watts of power from the utility company.

Thank you allenb. The roasts turn out really good compared to my old hot air popper roasts. (No comparison really) This machine allows me to draw out the profile in a proper way... slowly, albeit manually at present. I have to say there is a lot to learn about roasting, and what is best for my bean varieties from Peru. Any suggestions?

The spouting action was made better by using SS mesh from a MAF (mass air flow) from a spare car part. Very fine wire and strong. This allowed me to narrow the inlet with minimal resistance, upping the air velocity, and imparting more kinetic energy to a focused point in the center of the bean mass.

The limits of the food grade high temperature silicone in green is supposed to be stable to 450F, but I called the company and a technician/engineer said it should be fine with fluctuations to just about 500F. The inlet area part may be re-cast using a lead-free pewter that is good to a higher temp to allow more versatility in future roasts.

Not really. That was one example of roast time to show power consumption. It really depends on the profile that is desired... long roast or short roast. This is controlled manually with the POT's for desired heat level.

There is also a few minutes (2-3) to cool in the RC, and say a couple minutes for unloading/loading and assembling the RC. So with that profile, 4 complete batches per hour would be reasonable. Thanks.